It is already a conventional practice to incorporate enzymes into detergent compositions. Enzymes in detergent compositions serve as auxiliary detergents or washing promoters. Thus, for example, enzymes in laundry detergent compositions decompose or denature various kinds of dirt (or soil) and stains adhering to clothes, and enzymes in dishwashing detergent compositions decompose or denature fats and oils, proteins, starch and the like remaining on the dishware surface, to thereby facilitate and promote removal of various kinds of dirt. For the removal of starchy dirt, in particular, .alpha.-amylase has been used so far. Enhanced detergency can be attained by immersing articles to be washed in an .alpha.-amylase-containing washing solution for a prolonged period of time. However, .alpha.-amylase can hardly function to a satisfactory extent within an ordinary washing time of 5 to 30 minutes.
To keep abreast with the recent rapid spread of automatic dishwashers not only among restaurants and other commercial facilities but also among homes, detergent compositions for use in automatic-dishwashing have been developed. Thus, for example, automatic-dishwashing detergent compositions, which are available on the market in the powder form and constitute a typical class among dishwashing detergent compositions, comprise, as major components, inorganic alkaline substances or builders, such as pyrophosphates, tripolyphosphates, orthophosphates, carbonates, bicarbonates, sesquicarbonates, silicates and borates, and, as minor components, surfactants or lipase for enhancing fatty or oily dirt detergency, .alpha.-amylase for enhancing starchy dirt detergency, protease for enhancing proteinaceous dirt detergency, bleaching agents for enhanching pigment stain (e.g., tea stain) detergency, and so forth, as necessary or as desired. In automatic-dishwashing detergent compositions in the liquid form, surfactants are the major components, with enzymes and other ingredients added in small amounts.
Incorporation of .alpha.-amylase and the like enzymes into automatic-dishwashing detergent compositions, however, still cannot result in satisfactory removal of starchy dirt firmly adhering to dishware within a short period of time. Improvements are desired.